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A 7-month-old girl with acute biphenotypic leukemia [t(4;11)] had accompanying anemia, thrombocytopenia, and a white blood cell count of 535,000/microL with 98% blasts. Before instituting chemotherapy, therapeutic leukapheresis was done to reduce the threat of complications from leukostasis. Using a Cobe Spectra blood cell separator primed with modified blood, we processed 1,395 mL of her blood, removing 201 mL of the buffy coat containing 5.8 x 10(10) white blood cells. This reduced the WBC count to 301,000/microL. Only a single procedure was done, without significant complications. The rationale of this preparatory cytoreduction is discussed critically. Subsequent chemotherapy resulted in a long-lasting remission.

The hematologic manifestations and clinical course are described for six children and adolescents with bone marrow monosomy 7. One child with secondary acute myelogenous leukemia had monosomy 7 plus a marker chromosome; the remaining patients had marrow monosomy 7 as the only karyotypic abnormality. The hematologic abnormalities were diverse, but the majority of patients had a smoldering preleukemic or myeloproliferative phase. Leukemic blasts were either undifferentiated or demonstrated evidence of myeloid differentiation. All patients responded poorly to antileukemic therapy. Bone marrow monosomy 7 was observed in one patient with severe marrow hypoplasia. Antileukemic therapy in another patient with greater than 30 per cent marrow blasts was associated with the development of a bone marrow myeloproliferative disorder with persistence of the monosomy 7 karyotype. We speculate that monosomy 7 may be a specific marker for a pluripotent hematopoietic stem cell abnormality that is associated with either blastic leukemia or a myeloproliferative disorder.

Serum varicella-zoster (VZ) antibody titers were determined by a simple, indirect immunofluorescent antibody technique in 50 children with leukemia or non-Hodgkin's lymphoma. Sixteen children had initial antibody titers that were not detectable at a serum dilution of 1:8 and were considered to be susceptible to varicella. Thirty-one patients had initial serum VZ antibody titers of 1:16 or greater, while three had levels of 1:8. The serum antibody titer was 1:8 or greater in 16 children with a history of varicella. Seven episodes of localized herpes zoster were observed in children whose VZ titer was 1:8 or greater prior to onset. Two nonfatal infections with primary varicella developed in children with leukemia in remission whose initial titers were less than 1:8 and were associated with a convalescent rise in VZ antibody to levels greater than 1:16. Three susceptible children received zoster immune plasma or zoster immune globulin for varicella exposure, causing a transient rise in serum VZ titer. The assessment of serum VZ titer by this immunofluorescent antibody technique combined with the prior varicella history is useful in defining the population of children with leukemia and non-Hodgkin's lymphoma who are susceptible to primary varicella.

Neutrophil (PMN) bactericidal activity, phagocytosis, and nitroblue tetrazolium (NBT) reduction were evaluated in 18 children with untreated or relapsing acute leukemia and 20 children in hematologic remission. Half of the patients in relapse demonstrated abnormal PMN bactericidal activity, while remission patients had essentially normal PMN bactericidal activity. Phagocytosis of Staphylococcus aureus was normal in relapse and remission subjects. NBT reduction by PMN's of leukemic patients was significantly lower than that of controls, but there was no correlation between decreased NBT-reductase activity and decreased bactericidal power. Six patients in remission had received intensive chemotherapy for more than 4 years, and all demonstrated normal PMN functions. Among relapse patients with abnormal PMN bactericidal activity 63% eventually developed severe bacterial infections. By comparison, 20% of the relapse patients with normal PMN bactericidal activity subsequently developed severe infections. The PMN dysfunction observed in relapse patients suggests that abnormal PMN bactericidal activity may contribute the increased susceptibility to bacterial infections during leukemic relapse.